Follow-up to sha256-armv4.pl in cooperation with Ard Biesheuvel
(Linaro) and Sami Tolvanen (Google).

(Imported from upstream's b1a5d1c652086257930a1f62ae51c9cdee654b2c.)

Change-Id: Ibc4f289cc8f499924ade8d6b8d494f53bc08bda7
Reviewed-on: https://boringssl-review.googlesource.com/4467
Reviewed-by: Adam Langley <agl@google.com>

(Imported from upstream's e390ae50e0)

Change-Id: Ifee85b0936c06c42cc7c09f8327d15fec51da48a
Reviewed-on: https://boringssl-review.googlesource.com/3832
Reviewed-by: Adam Langley <agl@google.com>

This is an import from ARM. Without this, one of the Android builds of
BoringSSL was failing with:
  (sha512-armv4.o): requires unsupported dynamic reloc R_ARM_REL32; recompile with -fPIC

This is (I believe) a very misleading error message. The R_ARM_REL32
relocation type is the correct type for position independent code. But
unless the target symbol is hidden then the linker doesn't know that
it's not going to be overridden by a different ELF module.

Chromium probably gets away with this because of different default
compiler flags than Android.

Change-Id: I967eabc4d6b33d1e6635caaf6e7a306e4e77c101
Reviewed-on: https://boringssl-review.googlesource.com/3471
Reviewed-by: Adam Langley <agl@google.com>

This change syncs these asm files with upstream's 1.0.2 branch. The
important change is that they contain ARMv8 code that allows 32-bit ARM
code to use the hardware support in ARMv8 when running on such a chip.

Change-Id: Id37cb1ff0cbc98a8e328612df7cf60340ca96064
Reviewed-on: https://boringssl-review.googlesource.com/2921
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Adam Langley <agl@google.com>

This change marks public symbols as dynamically exported. This means
that it becomes viable to build a shared library of libcrypto and libssl
with -fvisibility=hidden.

On Windows, one not only needs to mark functions for export in a
component, but also for import when using them from a different
component. Because of this we have to build with
|BORINGSSL_IMPLEMENTATION| defined when building the code. Other
components, when including our headers, won't have that defined and then
the |OPENSSL_EXPORT| tag becomes an import tag instead. See the #defines
in base.h

In the asm code, symbols are now hidden by default and those that need
to be exported are wrapped by a C function.

In order to support Chromium, a couple of libssl functions were moved to
ssl.h from ssl_locl.h: ssl_get_new_session and ssl_update_cache.

Change-Id: Ib4b76e2f1983ee066e7806c24721e8626d08a261
Reviewed-on: https://boringssl-review.googlesource.com/1350
Reviewed-by: Adam Langley <agl@google.com>

Initial fork from f2d678e6e8 (1.0.2 beta).

(This change contains substantial changes from the original and
effectively starts a new history.)